Just so you know, the run of the mill loctite silicone sealant will work for the diff. For example, the ultra-black will be suffice. For any of you old timers, Permatex Aviation form-a-gasket is excellent (Indian Head Shellac works too) is a cheap alternative.
FYI: Red loctite all of the diff cover bolts if you track your car and run solid bushings. This is a great way to reduce your maintenance time between events (I use a bunch of red loctite on my cars).